1. Field of the Invention
The invention relates to an electronic module for connection of sensors or actuators to a bus line, with a housing, with an electronic unit, with at least one jack or a plug for connection of electrical, optical, pneumatic or hydraulic lines, with at least one jack or one plug for connection of at least one bus line.
2. Description of Related Art
These electronic modules are used to connect several sensors or actuators to a bus line via which sensors and actuators are connected both to power and also to a central control. The bus line is generally an unshielded two-lead ribbon cable or standard round cable via which signals and power are transmitted at the same time. The electronic module is generally comprised of a circuit board which is assembled according to requirements and which is kept in a housing. If the jack and/or the plug is used for connection of pneumatic or hydraulic lines, pneumatic valves and/or hydraulic valves are also installed in the electronic unit. The advantage of known bus systems is that it is no longer necessary for each actuator or sensor to be wired individually, but instead, only one bus line is needed to connect all actuators and sensors to the control. In this way, the system becomes much easier to install and start-up of machinery and systems become simpler.
In order to be able to quickly and easily connect the individual actuators and sensors to the bus line, the initially described electronic module is used, which is often also called an actuator-sensor box or actuator-sensor module. The jacks for the sensors are called inputs and the jacks for the actuators are called outputs so that the electronic modules are also called input/output modules or I/O modules.
A first type of module is comprised of a module top part, the so-called user module, and a module bottom part, the so-called coupling module (see, published German Patent Application DE 197 56 167 A1). The coupling module is used to connect the user module to the bus line, for which there are the corresponding pin or knife-edge contacts for making contact with the bus line in the coupling module. The user module and the coupling module are likewise electrically connected to one another via pin contacts and mechanically connected to one another via screws in the user module. The user modules differ especially in the number of terminal jacks or sockets, the majority of the user modules having four or eight M12 jacks for connection of a corresponding number of binary devices.
In another type of electronic module, the connection to the bus line takes place, not via the coupling module, but via a separate line which is connected to a jack or plug which is located in the module. For this type of module, the housing is, likewise, also made in two-parts, so that the housing has a housing top part and a housing bottom part. However, the housing bottom part does not have the function of the above described coupling module since the connection to the bus line does not take place via the housing bottom part. Instead, the housing bottom part is used for connection of the electronic module to a support surface, for example, to the wall of a tank or machine, so that the housing bottom part is used as a mounting plate. Furthermore, these electronic modules generally have a cuboidal plastic housing which, for connection of the electronic module, rest over a large area on a straight support surface which is largely parallel to the housing, the fixing of the electronic module taking place using screws, for which there are the corresponding holes in the housing.
Under ambient conditions with loading by permanently elevated humidity or in applications in which cleaning of the electronic modules takes place with a water jet, especially with a high pressure cleaner such as, for example, in the foodstuffs or beverage industry, the known electronic modules can hardly be used. Especially in the food and beverage domain are very high demands imposed not only on the sealing of the housing, but also on the capability of the housing to be cleaned, especially in the transition area to the support surface. Here, the deposition of germs on the housing or in the transition area from the housing to the support surface must be avoided as much as possible. The resting of the cuboidal housing on the support surface over a large area however entails the danger of deposition of germs since the available support surface is generally relatively uneven and rough so that germs can easily settle in the transition area from the housing to the support surface.